Maskless epitaxial lateral overgrowth of GaN layers on structured Si(111) substrates

Abstract

GaN layers are laterally overgrown by metalorganic chemical vapor deposition on structured Si(111) substrates in a single growth process. The substrates are structured with parallel grooves along the Si 〈1–10〉 or perpendicular to the Si 〈1–10〉 direction by standard photolithography and subsequent dry etching. Due to the anisotropic chemical dry etch process, the remaining Si ridges are underetched. The GaN layer grows nearly exclusively on the bottom of the grooves and on the top of the ridges between the grooves. These two growth fronts are completely separated from each other. As a consequence, the GaN layer growing from the ridge area between grooves can extend over the grooves. This process is similar to the so called pendeo-epitaxy process, but is completely mask free during growth and does not require any growth interruption. The improvement of the crystalline and the optical quality of the GaN layer is demonstrated by atomic force microscopy and cathodoluminescence spectroscopy.

Epitaxial Lateral Overgrowth of GaN on Si (111) Substrates Using High‐Dose, N+ Ion Implantation

“…Therefore, many trials have been done for a maskless or single-step ELO process. [6,7] In this study, an ELOG GaN layer was obtained on a Si(111) substrate by a single-step deposition without the regrowth which is needed for the oxide or nitride deposition. Patterning using high-dose, N þ ion implantation was employed for the first time to form an ELOG GaN layer.…”

Characterization of growth defects in thin GaN layers with X‐ray microbeam

“…Various lateral epitaxial overgrowth (LEO) techniques have recently been developed which greatly reduce the density of threading dislocations. One of them is cantilever epitaxy (CE) with GaN wings overhanging over the trenches produced in Si substrates by photolithography methods [5][6][7][8][9]. Very often the laterally grown wings are found to be crystallographically tilted.…”

Epitaxial lateral overgrowth of GaN on 4 inch Si(111) by MOVPE

“…However, the growth front is not straight in ELOG with LT AlN interlayers partially due to 3-dimensional growth of GaN on LT AlN. Thus, it is difficult to achieve a smooth and fully coalesced layer [5]. ELOG with AlN/GaN superlattices is more practical and a completely smooth layer was achieved over a 7 µm Si x N y stripe even though some cracks were still observed after coalescence [6].…”

“…In the literature, low temperature (LT) AlN interlayers and AlN/GaN superlattices have been used in ELOG on silicon to prevent cracking [5,6]. However, the growth front is not straight in ELOG with LT AlN interlayers partially due to 3-dimensional growth of GaN on LT AlN.…”